1. Field of the Invention
Embodiments of the invention relate to a solid-state light engine that is directly compatible with alternating current (AC) input power, without the need for a separate rectification module, but that can also alternatively be powered by direct current (DC) input power.
2. Related Art
In many lighting applications, solid-state light engines are superior to conventional incandescent lamps. Beneficially, solid-state light engines can, in certain circumstances, achieve an almost 20% improvement in efficiency and an extended lifetime (e.g. exceeding 50,000 hours) as compared to incandescent lamps.
Traditional solid-state light engines are powered by a direct current or pulsating direct current drive. As such, to drive the light engine using an AC power source, the AC input line must first be conditioned. Power-conditioning commonly involves the rectification of AC input power, typically achieved by inserting rectifier diodes in a bridge configuration, as well as a means of limiting current, such as a series resistance or reactance in the power path. However, the addition of such electronic components into the power path may increase manufacturing costs and complexity, and can cause a decrease in the lifetime (or time to failure) of the light engine, and can decrease efficiency due to power loss.
To avoid the performance-related issues caused by the insertion of power conditioning elements into the power path, some standard solid-state light engines are powered directly from the AC line. However, the direct AC powering of a light engine causes the light output to pulsate at the frequency of the AC power source, typically in the range of 50 to 60 Hz. This line frequency pulsation can produce eye fatigue or annoyance when viewed, even in cases where the engine is viewed for a short period of time.
Accordingly, there is a need for a solid state light engine that is directly compatible with an AC input power source, which does not exhibit the deleterious pulsation effects generated by a direct AC powering arrangement, and/or which does not require the use of separate power conditioning or rectification circuitry.